The first staple you should get is salt, lots of it. Sugar isn't a necessity. Preserving food is your first concern as there would be long periods of no kill. If animals were being hunted consistently they sure wouldn't hang around as they sometimes do now. Also your body needs salt, just not near as much as we get now.
Vitamens through a long hard winter. Don't see too many oranges growing here. So what do you eat to suppliment that? Boil up some pine needles-yuck! O ya and how are you going to boil them? People that lived here for thousands of years had a hard time surviving. And some think they could do it? How many here actually spent a night in a tent in the winter? It's not pleasant even on a mild winter night with proper gear (not to me anyway). So you have all this gear. how are you going to carry it all? Where are you going to keep it so the animals don't take it away. How many of you have ever stalked an animal? They see and hear you a a lot sooner than you can see or hear them.
If it ever gets that bad (it wont) make sure you bring a shovel too. You will spend a lot of time burying the dead come spring.